Summary: A study conducted by researchers from Université de Montreal and Université de Poitiers found that daily full-body cryostimulation—spending five minutes in a chamber cooled to -90°C—can improve sleep quality and mood in healthy young adults. The benefits, including a significant increase in slow-wave sleep, the most restorative sleep phase, appeared after five consecutive sessions. Women showed greater improvement than men in both perceived sleep quality and anxiety levels. Researchers highlight potential applications of cryostimulation for individuals with sleep disorders, elite athletes, and those with chronic inflammation or mild dementia.
Key Takeaways:
- Cryostimulation Boosts Restorative Sleep: Spending five minutes daily in a -90°C chamber over five consecutive days increased slow-wave sleep duration and improved overall sleep quality.
- Gender Differences Observed: Women experienced greater improvements in perceived sleep quality and reductions in anxiety compared to men.
- Potential Beyond Sleep Benefits: Cryostimulation could aid recovery for athletes, support people with chronic inflammation or mild dementia, and benefit those with sleep disorders when combined with other therapies, researchers say.
Daily full-body cryostimulation—exposure to extreme cold—improves sleep quality and mood in healthy young men and women, according to new research by scientists at Université de Montreal and Université de Poitiers in France.
“The use of cold for therapeutic purposes goes back to ancient Greece,” says Olivier Dupuy, an associate professor at UdeM’s School of Kinesiology and Physical Activity Sciences, in a release. “But we still don’t know the exact amount of cold needed to produce sleep benefits.”
In a study published in Cryobiology, Dupuy and his Poitiers colleagues Laurent Bosquet and Benoit Dugué describe having recruited nine women and 11 men, average age 23, to undergo daily cryostimulation sessions for five consecutive days.
The experiment was then repeated without cryostimulation to isolate its effects on sleep.
Each cryostimulation session consisted of spending five minutes in a chamber cooled to -90°C.
“While in the chamber, the subjects wore underwear or a swimsuit and socks, croc-type shoes, mittens, and a tuque to protect their extremities from the intense cold,” says Dupuy in a release.
Following the cryostimulation, the subjects went about their normal daily activities until bedtime, avoiding alcohol consumption and any activity, physical or otherwise, that could affect their sleep.
At bedtime, they were fitted with a wireless headband equipped with brain activity sensors, a wrist actigraph, and a heart-rate sensor to measure the effects of cryostimulation on their physiology and sleep patterns. Each morning, they completed a questionnaire to assess perceived sleep quality.
One Session Not Enough
The data showed that one cryostimulation session was not enough to improve sleep: The benefits appeared only after five consecutive sessions.
“Our sleep architecture analysis revealed a significant increase in the duration of slow-wave sleep during nights following cryostimulation compared to nights without cryostimulation,” says Dupuy in a release. “Slow-wave sleep, considered the most restorative phase of sleep, increased by an average of 7.3 minutes during the first two sleep cycles.”
The study also showed marked gender differences, with women benefiting from cryostimulation more than men. Women reported an improvement in perceived sleep quality on the third and fourth nights of the protocol, from an average of 3.4 on a scale of 1 to 5 without cryostimulation to 3.9 with cryostimulation, and their perceived level of anxiety decreased from 43 to 38.
“Women and men did not have identical responses,” says Dupuy in a release. “This suggests that the dose of cold should be adjusted according to gender, although this requires further study.”
Although the changes observed may seem small, they are promising and could pave the way for a variety of applications, he adds, saying, “While this study focused on people who generally sleep well, we believe that cryostimulation could be especially beneficial for people with sleep problems.”
Other Uses Highlighted
The potential uses don’t stop there. “For elite athletes, it could help with recovery, while for the general population, it could help people with chronic inflammation or mild dementia when used in combination with physical exercise,” says Dupuy in a release.
The study was part of a larger research program on cryostimulation. Dupuy and his colleagues received funding to study its use by athletes preparing for the Paris Olympics in 2024 and two more scientific papers on the link between cold and sleep will be published soon.
Many issues remain to be explored, including the long-term effects of cryostimulation and the mechanism behind its clinical effects.
“But one thing is clear: This is not a placebo effect,” says Dupuy in a release. “Other studies have demonstrated similar positive effects in elite athletes.”
In some countries, such as Poland, the cost of cryostimulation sessions is already covered by public health insurance plans. “With these encouraging new data, cryostimulation could well be adopted in clinical settings in the fields of medicine, kinesiology and physiotherapy,” Dupuy concludes.
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